Self-regulating electric converter



(No Model.)

T. SPENOER. sEL1 REGULATING ELECTRIC GONVEETER. No. 457,40'7. PatentedAug. 11, 1891.

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UNITED STATES PATENT OFFICE.

THOMAS SPENCER, OF PITTSIURG, PENNSYLVANIA.

SELF-REGULATING ELECTRIC CONVERTER.

SPECIPICATION forming part of Letters Patent No. 457,40'7, dated August11, 1891.

Application filed December 17, 1890. Serial No. 875.043. (No model.)

` useful Improvements in Self-Regulating Electric Oonverters, of whichthe following is a specifieation.

The invention relates to certain improvements in electric converters andthe method of causing them to automatically Compensate for changes whichresultfrom variations in load.

In certain forms of converters the primary and secondary coils areplaced side by side upon a soft-iron core. XVhen currents traverse theprimary coil, lines of force are generated which traverse or thread thesecondary coils and develop therein an electro-motive force, which inturn establishes current in the secondary coil, if its circuit beclosed. The lines of force developed by the flow of primary currents forthe most part complete their --ircuit through the iron core; but inpractice 'iiome of them escape through the air and thus mio not threadall the convolutions of the secondary coil. In practice the number oflines thus escaping is greater as the current flowng in the secondary isgreater, so that at full ^oad the number of lines of force actually,hreading the secondary, and consequently the effective, electro-motiveforce developed therein isless than at small load. By my invention thiseffect is utilized for governing` the Operation of the converter andcausing the electro-motive force to be maintained the same or evenincreased at full load.

The invention consists in placing upon the core a few convolutions ofsecondary wire wound in the reverse direction from the main portionthereof, and in locating these convolutions so that the escaping linesof force do not thread them. From this construction it results that whenbut little current is flowing in the secondary, and consequently butlittle opposition is offered to the flow of the lines of force throughthe core, practically all these lines of force thread both the main andthe reversed secondary convolutions. The effect of the reversedconvolutions is therefore to neutralize an equivalent number of the mainThe Consequent eifective secconvolutions.

ondary electro-motive force developed is the resultant of the twoopposing electro-motivc forces in the two sets of convolutions. If nowthe resistance of the secondary circuit be diminished and more currentbe permitted to flow, then more of the lines of force will completetheir circuit outside of the iron core, and thus fail to traverse thereversed secondary convolutions. The reversed convolutions Will nolonger neutralize the same number of main con volutions, and theresultant secondary electro-motive force will therefore becorrespondngly increased.

In the accompanyingdrawingIhave shown diagrammatically a converterillustrating one plan of carrying' the invention into practice.

Referring to the tigure, A represents a core of any convenient type. Itis wound with coils P and S, placed side by side. The primary coil P isdesigned to be Connected in any suitable constant-potentialalternating-current circuit. The secondary coil S is composed of twosections s' and .92. The sections' is the main section and intervenesbetween the primary coil P and the section 32. This latter sectioncomprises comparatively few convolutions, and is wound in the reversedirection from the section s', so that the electromotive force developedtherein is opposed to that developed in the section s'. The current atany time flowing in the secondary coil of the Converter is approximatelyone hundred and eighty degrees later than the current fiowing in theprimary. From this it follows that the magno-motive force developed bythe flow of secondary currents is approximately one hundred and eightydegrees later than that produced by the primary current. The flow of theprimary lines of force through the secondary coils is therefore due tothe dilference between these two opposing magno-motive forces, and asthe current tlowing in the secondary circuit increases, the increasedopposition offered by reason of the increased secondary magno-mot-iveforce causes more of the primary lines of force to complete theircircuit outside of the secondary coil, or without traversing the entirelength of the secondary coil. Therefore when the resistance of thesecondary Circuit is high and but little work is being done, theopposition to the flow of lines of force through the iron core is TOOsmall, and practically all those generated by the current flowing in theprimary coil thread both sections of the secondary coil. When, however,the load is increased and the resistance of the secondary Circuit islowered, then the increased current flowing,` in the coil S results ingreater opposition to the fiow of lines of force therethrough, andconsequently more will escape through the air-space without traversingthe reversed secondary winding` 82, as indicated by the arrows xx in thedrawing. From this it follows that the resultant electromotive force inthe secondary coil will be increased, since the opposing electro-motiveforce in the section .92 is relatively less.

The relative proportions of the two sections s' and s2 may be varied toobtain different degrees of compensation or amounts of regulation. Thusit may be desired to compensate merely for the drop in the converter dueto the resistance of the conductor, or it may be desired also tocompensate for the loss in the conductors cornprising` the work-Circuit,so that the amount of reverse winding must be made to suit therequirements of different cases.

I elaim as iny invention-e 1. An eleetric converter consistin` of a coreof soft iron, a primary coil carried thcreby, a secondary coil Woundupon a different portion of the core and having a portion of itsconvolutions reinote from the primary coil wound in the reversedirection from the balance thereof.

2. In an electric converter,a secondary coil having a few of itsconvolutions wound in the opposite direction from the main portion.

3. The method of automatically governing the eifective electro-motiveforce developed in the secondary coil of an electrie converter, whichconsists in generating in that coil two opposing electro-motive forcesand causing` the value of the less of these electro-motive forces todiminish as the current fiowing in the secondary circuit is increased.

In testimony whereof I have hereunto subscribed my name this Sth day ofDecember, A. D. 1890.

THOMAS SPENCER.

Witnesses:

CHARLEs A. TERRY, J. W. SMITH.

Correction in Letters Pa telnt No. 457,407.

It is hereby eertified that in Letters Patent No. 457,407, grantedAugust 11, 1891, upon the application of Thomas Speneer, of Pittsburg,Pennsylvania, for an improve.- ment in Self-Begulating ElectricGonverters, an error appears in the printed specifieation requiring thefollowing oorreetion, Viz.: In line 43, page 2, the Word less shouldread lesser; and that the said Letters Patent should be read With thisoorreetiou therein that the same may oonform to the record of the casein the Patent Office.

Signed, eountersigned, and sealed thislth day of October, A. D. 1891.

GYRUS BUSSEY, Assistcmt Secretary of the Interior.

[SEAL] Gountersigned W. E. SIMoNDs,

Ooomnissimwr of Patents.

Correction in Letters Patent No. 457,407.

pon the application of Thomas Spencer', ment in Self-Regulating ElectricGonverters, an error appears in the printed specification requiring thefollowing correction, viz.: should read esser; and that the therein thatthe same may conform to the record of the case in the Patent Office.

Signed, countersigned, and sealed this lth day of October, A. D. 1891.

v GYRUS BUSSEY, Assistcmt Secrtm'y of the Interior;

In line 43, page 2, the word less7 said Letters Patent should be readwith this correctior [SEAL] i Oountersigned:

W. E. SIMONDS,

Gmnmssoner of Patefnts.

It is hereby certified that in Letters Patent No. 457 ,407, grantedAugust 11, 1891 of Pittsburg, Pennsylvania, forian irhproye;

